Folded Floating-Gate CMOS Biosensor for the Detection of Charged Biochemical Molecules

A folded floating-gate CMOS biosensor is realized for the detection of charged biochemical molecules. The biosensor comprises a field-effect transistor with a floating-gate, a control-gate, and a sensing area. Charged biochemical molecules placed on the sensing area induce a voltage on the floating-gate and a relative shift in the threshold characteristics. Compared to conventional devices, the floating-gate here is folded to span the entire device. This allows us to place the sensing area above the field-effect transistor (FET), thus reducing the total device area. The fabricated devices show good sensitivity to the polarity and concentration of charged poly amino acids. Possible applications of the device include electronic detection of spatial and temporal charge migration such as in biological processes.